1. Field of Invention
This invention relates to torque limiting fasteners and, in particular, to torque limited pressed, forged, or stamped metal nuts.
2. Brief Statement of the Prior Art
Torque limiting fasteners are commonly used in the aerospace industry. Typically, the torque limiting fasteners include a frangible fastener having a threaded collar and a distal wrenching ring separated by a notched section that provides a predetermined limiting torque which, when exceeded, permits the wrenching ring to shear from the threaded collar.
In U.S. Pat. No. 4,068,555, there is disclosed an inherently torque limited nut which has a drive ring that is secured to the nut body by a splined engagement. The drive ring is formed of a material of low shear strength, e.g., certain plastics, and the number and spacing of the splines provides a control of the torque which can be applied to the fastener through the drive ring.
Other torque limiting techniques have used drive collars which are linked to a fastener through radial pins which shear when the predetermined torque is exceeded; see U.S. Pat. Nos. 3,267,792 and 3,460,428.
Stamped or pressed metal fasteners are also used in the aerospace industry. These metal fasteners are light weight and self locking from the natural resiliency of the fastener.
Heretofore, there has been no torque limiting application of the stamped metal fasteners despite their popularity.